// Magic Software, Inc.
// http://www.magic-software.com
// Copyright (c) 2000, All Rights Reserved
//
// Source code from Magic Software is supplied under the terms of a license
// agreement and may not be copied or disclosed except in accordance with the
// terms of that agreement.  The various license agreements may be found at
// the Magic Software web site.  This file is subject to the license
//
// FREE SOURCE CODE
// http://www.magic-software.com/License/free.pdf

#ifndef MGCSPECIALFUNCTION_H
#define MGCSPECIALFUNCTION_H

#include "MgcMath.h"


class MgcSpecialFunction
{
public:
    // gamma and related functions
    static MgcReal LogGamma (MgcReal fX);
    static MgcReal Gamma (MgcReal fX);
    static MgcReal IncompleteGamma (MgcReal fA, MgcReal fX);

    // error functions
    static MgcReal Erf (MgcReal fX);   // polynomial approximation
    static MgcReal Erfc (MgcReal fX);  // erfc(x) = 1-erf(x)

    // modified Bessel functions of order 0 and 1
    static MgcReal ModBessel0 (MgcReal fX);
    static MgcReal ModBessel1 (MgcReal fX);

protected:
    // series form (used when fX < 1+fA)
    static MgcReal IncompleteGammaS (MgcReal fA, MgcReal fX);

    // continued fraction form (used when fX >= 1+fA)
    static MgcReal IncompleteGammaCF (MgcReal fA, MgcReal fX);
};

#endif
